Ocean iron fertilization may amplify climate change pressures on marine animal biomass for limited climate benefit. Glob Chang Biol. 2023 Sep;29(18):5250
Research since the 1990s has shown that ocean iron fertilization does lead to increased seawater CO₂ uptake due to enhanced photosynthesis.
Ocean iron fertilization (OIF) is generally considered to constitute a potential geoengineering method with which to sequester more CO2 in the oceans.
Iron fertilization is a Carbon Dioxide Removal (CDR) technique that would artificially add iron to the ocean’s surface to stimulate growth of phytoplankton. When the plume of dust or ash settles over the ocean’s surface, it triggers massive blooms of phytoplankton that remove substantial amounts of carbon dioxide from the atmosphere. Iron fertilization is a Carbon Dioxide Removal (CDR) technique that would mimic this natural system, artificially adding iron to the ocean’s surface to stimulate growth of phytoplankton. If relatively small amounts of iron can be added to the ocean’s surface to effectively remove large amounts of carbon dioxide from the atmosphere, iron fertilization has the potential to play a pivotal role in reducing additional impacts associated with climate change. Until experiments are done to test these potential outcomes and determine how much carbon can be sequestered in the ocean depths, iron fertilization should not be put to use as a method of slowing climate change. ### Fertilizing the Ocean with Iron.
Ocean fertilization adds nutrients, such as iron, to the surface of the ocean to enhance CO2 uptake by marine algae (phytoplankton) via
Large-scale ocean iron fertilization is one of several strategies that could help remove carbon dioxide, but new research published this week in Global Change Biology by a Bigelow Laboratory for Ocean Sciences researcher and colleagues shows that it might also negatively affect marine ecosystems in far corners of the ocean. The models did show that iron fertilization could remove up to 45 gigatonnes of carbon dioxide from the ocean surface between 2005 and 2100. Large-scale ocean iron fertilization is one of several strategies that could help remove carbon dioxide, but new research published this week in Global Change Biology by a Bigelow Laboratory for Ocean Sciences researcher and colleagues shows that it might also negatively affect marine ecosystems in far corners of the ocean. The models did show that iron fertilization could remove up to 45 gigatonnes of carbon dioxide from the ocean surface between 2005 and 2100.
# Ocean iron fertilization commercialization: bad idea; Continued research: good idea. Ocean Iron Fertilization (OIF) is an ocean-based strategy that involves the addition of iron to the sunlit upper layers of the ocean in iron-limited areas such as the Southern Ocean in order to stimulate marine phytoplankton growth and increase drawdown of carbon dioxide. Authors of a recent technology review in the *Journal of Science Policy & Governance* argue that a market-based approach to Southern Ocean iron fertilization is not advisable, but recommends continued research into the matter. This study begins by asking whether or not fertilizing the Southern Ocean could actually create a sustainable carbon sink. A comprehensive literature review revealed that while iron fertilization almost certainly will stimulate new primary production, what is much less clear is how much of that carbon will sink out of the surface ocean and be sequestered long-term. Given the scientific uncertainty, it would be ill-advised to commercialize iron fertilization in emerging carbon offset markets.
DEEP-OCEAN STEWARDSHIP INITIATIVE Fig. 1 Elements of the biological pump (Fig. 1 From McClain (2010) American Scientist) Deep Ocean Climate Intervention Impacts Deep Ocean Climate Intervention Impacts Ocean Fertilization Key Points DECEMBER 2021 Policy Brief Page 2 DOSI Scaling and Effectiveness The subarctic Northern Pacific, Eastern Equatorial Pacific and Southern Ocean are high-nutrient, low-chlorophyll regions where iron scarcity limits phytoplankton growth, and thus have been proposed for OIF (Yoon et al., 2018, GESAMP, 2019). The alteration of natural phytoplankton communities may result in changes in the seasonality of particulate organic carbon flux to the deep-sea floor (benthic-pelagic coupling) and in compositions of phytoplankton species in the marine snow, potentially impacting deep-sea benthic communities that rely on food from the ocean surface (Billet et al., 1983; Gooday, 1988; Graf, 1989; Ruhl and Smith, 2004; Nomaki et al., 2021).